A method for adjusting a resonator in an oscillator is described in German Patent Application No. DE 101 19 033, which stands out in that a dielectric material as resonator in the oscillator is purposefully removed (ablated) by laser pulses until a targeted frequency is achieved. As the laser, in this case, preferably an excimer laser or a solid-state laser is used.
In this method, it is a disadvantage that, during the removal of the dielectric material, in order to set the frequency of oscillation, a part of these ablation products condenses on the pill-box resonator or on the immediate circuit environment and there forms a dust layer or a firmly adhering condensate film. This deposit first of all lowers the resonator frequency again and leads, especially by slow ablation over the service life of the resonator, to a creeping frequency increase, and thereby to a reliability problem. The usual cleaning methods are not applicable in this case, since the screening box, having only a small aperture to let through the laser beam, does not permit any effective cleaning possibilities.